Process of burning cement clinker.



No 820,484. I PATENTED 1 196,

- H. L DOL-IERTY. S 0? BURNING CEMENT CLi'NKEEJ,

PROCESS APPLICATION FILED 1130.12, 1905 1 akin GM v d 1 C S pro unli i S 21 .2.1 cu 6 A6 8 f u I 5 I AU 2 ru an n b E 1 7L 1 .2 a m 61 i lru Vanna"; 1 m

30 the my '50 amp by the forces and materials concerned in the process are caused to cooperate in the relations necessary for its exercise, which apparatus is also claimed herein.

In the accompanying drawing is illustrated a side elevation of a cement-burning furnace equipped to carry out this invention.

In the drawing, 1 is the inclined rotary barrel of a so-called horizontal cement-kiln similar to the ordinary although permissibly longer than usual. The barrel has a refractory lining 2, and at its upper end is the stack 3. At this end is also a screw conveyer or contains a fan-blower 10, which serves to hood.

draw back a small portion or modicum of the inert gases or products of substantially com plete combustion and force them into the kiln in company with the powdered fuel in predetermined proportion and in company with a predetermined volume of air drawn into the pipe 9 on the suction side of the fan at the point 11,whereat is an adjustable valve or damper for regulating the proportion of air, this damper being conveniently operated by a rod connected toa lever placed. near the There is also a damper l 2 in the trunk of thepipe for regulating the proportion ol stack-gas, althougl'i said damper is not co1nmonly changed after having been once set for favorable conditions of operation. The vari'ation in the roportion cl oxygen in the blast is accomp ished simply by adjusting the valve 11. The wider this damper is opened the greater the amount of air admitted and the smaller is the proportion of staclegas returned, for the reason tl'iat the fan can exhaust only a ei'inite volume at a given speed, and therefore increasing the volume oi air means d cc reusing the volume of stack-gas, and conversely. The kiln-gases contain a percentage of carbon dioxid ironi the calcination of the lime well as from combustion.

In a well-constructed kiln operating by my rocess approximately thirty per cent. otcaron dioxid is present in thestack-gases. Gom bustion may be so conducted as to be sub stantially com .lete in the kiln, so that substantially no tree oxygen need be present. The proportion of the total kiln-gases returned de ends somewhat upon their com position and temperature and also on the quality, temperature, and character of lame desired, tc. It withdrawn from the stack, the

" as possible.

eeaeas percentage of carbon dioxid will be found much lower than if taken from the mouth of the kiln, owing to the infiltration of air in the space between the kiln and the surrounding Wall at its u per endj Frequently the stackgases with rawn from the stack itself will contain not over ten per cent. of carbon dioxid. The amount of diluent gas returned may be ga ed a proximately by the amount of carbon dioxi for while the carbon dioxid is not the principal diluent, nitrogen being the preponderating gas present, yet as the carbon dioxid bears a fairly constant ratio to the nitrogen the former serves as an index of the dilution. In the mixture entering the kiln I prefer to have not less than one per cent. and not over six per cent. of carbon dioxid or from approximately live per cent. to twenty per cent. of diluent gas. This variation may be secured by the simple adjustment of the dam er 11,. as abo e mentioned. The jet of air an coal is introduced into the kiln in such a way that 'a substantial impingement of the (lame against thematerial occurs. My process makes poss1ble the close contact of the heating agent with the material to be heated, and, as is evident, such a method of heat application results in a pronounced economy in fuel. Frequently the jet may be.

introduced horizontally and due to the in- 9 clination of the kiln and to, the height of the material in the kiln an impinging flame is effected without any downward inclination of said jet. It, is 'of course essential that air from extraneous sources be excluded as much For instance, air entering the lower part of the kiln through the clinkerdischarge opening or through the space he tween the end of the kiln and the hood has a tendency to lift the flame from the material by forming a stratum of cold air in the bottom of the barrel. Such practice, which, in fact, is customary in the present (la y, I have found to be unecononiical, for besides elevatin the liamc from the material to a considerable degree, thereby preventing its impingement, the eddies setup from the introduction of said extraneous air cause fluctuations in "the l'la'tne and h "l to irregular operation.

-Y Vhilc l have d. closed my preferred em borlimcnt the use of powdereocoal as the luel for producing clinker, I do not limit myself exclusively ,to such a fuel. The same principles apply in the burning of or natural gs and to a considerable degree, moreover, in the combustion of producer-gas.

in order to make the variation in the area, locality, and duration of the clinkering zone definitely periodic, I connect the damper 11, by means oi a rod or otherwise, to an eccentric working on a shaft driven at a suitable speed, thereby opening and closing the damper at definite intervals. It the material is of such a character that rings form frequently,

the periodicity of zone change may be l'requent. Under conditions of operation in whichrings are little liable to form I prefer to cause the variations to occur at longer intervals. While it is possible to operate the damper by hand, as shown, yet for sim' lieity of the operation it is perhaps preferab e to render the adjustment automatic, thereby minimizing the duties of the kiln operator.

Element 20 designates a disk revolved by any suitable means (not shown) and carrying a (pin 21, adapted to engage a ring 22, carrie by rod 23, when the automatic valve operation is desired. When the valve is to be operated by hand, another ring 24 on the rod 23 is to be made to engage a pin 25, car ried bylever 26.

What I claim is 1. Process of burning cement in rotarykilns which consists in conducting combustion of a carbonaceous fuel with air impoverished with respect to its content of oxygen, and in varying the content of oxygen eriodically, whereby kiln incrustation's are eliminated.

2. Process of burning Portland cement in inclined rotary kilns, said process consisting in burning a stream of carbonaceous fuel in an oxygenated draft; in varying the proper tion of -oxygen intermittently, and in impinging the resulting flame upon the cementitious material.

3. Process of burning Portland cement in inclined rotary barrels which consists in mixing a stream of powdered fuel with a stream of supporter of combustion under pressure; varying the composition of said supporter of combustion from time to .time, whereby the formation of obstructions in the path of travel of the flame is eliminated, and in bringing the mixture into contact with the cement material at an igniting temperature.

4. Process of burning Portland cement in inclined rotary kilns which consists in passing. a stream of cement-forming material continuously through said kiln from its upper to its lower end; in injecting a predetermined amount of company with a predetermined amount of air containing products of combustion; in periodically varying proportion of said products of combustion in a predetermined manner; in subjectingthe combustible t5 an igniting temperature; and in bringing the flame produced thereby into intimate contact with said material.

5. Process of burning Portland cement in inclined rotary cement-kilns which consists in introdiicing a stream of cement-forming maowdered coalinto said kiln in terial into the upper part of said kiln, and in causing same to travel downwardly to the lower end of said kiln; in mingling at the lower end of said kiln a stream of powdered coal with a predetermined amount of air containing products of substantially complete combustion; and periodically varying the composition of said products of combustion whereby the shifting of the. clinkering zone is periodically effected; in causing the flame produced by the combustion of said fuel to impinge upon the material; and in preventing the introduction of air from extraneous sources.

6. Process of burning Portland cement in inclined rotary cylindrical kilns; said process consisting in subjecting the cement material to an impin 'ng flame roduced by injecting a mixture 0 powdere coal and diluted air as a single jetagainst said material; and in periodically varying the degree of dilution of said diluted air.

7. Process of burning Portland cement in inclined rotary cylindrical kilns which consists in conducting the combustion of carbonaceous fuel with a supporter-pf combus-' which consists in burning carbonaceous fuel in contact with the cement material with a supporter of combustion containing carbon dioxid; and in intermittently varying the pipportion of said carbon dioxid-whereby n incrustations are minimized.

9. Process of burning Portland, cement in inclined rotary cylindrical barrels, said process consistin in exposing a flattened stream of cement- 'orming material to the calcining and clinkering action of a blast of powdered coal, said coal being introduced as a single jet with sufficient oxygen to complete combustion, and with other gases of an inert character; in subjecting the fuel mix tune to an i niting temperature whereby a flame of high temperature is developed; in

'- causing said flame to impinge upon said fiattened stream of cement material; in periodically varying the proportion of inert gases introduced with said coal; and in preventing the admission of air from extraneous sources. Signed at New York, in the county of New York and State of New York, this 5th day of December, A. D1905.

' HENRY L. DOHERTY. Witnesses:

FLETCHER P. ScoFrELD, J. (has. ANDREWS. 

